1. Field of the Invention
The present invention relates to a drawing apparatus that performs drawing overlaid with a shot formed on a substrate based on drawing stripe data that constitute drawing data.
2. Description of the Related Art
An electron beam drawing apparatus performs drawing by superimposition on shots on the substrate, so that coordinates of a plurality of shots (sample shots) on the substrate are measured. The measurement may be performed using an alignment mark formed for every shot. Further, based on an assumption that a coordinate of a design shot and a coordinate of an actual shot have a predetermined geometric conversion relationship, a parameter (coefficient) of the transformation may be determined by the measurement. In addition, the coordinate of the actual shot may be obtained based on the parameter and the coordinate of the design shot. Further, for example, if a coordinate (x, y) is measured for each of a plurality of marks at every shot, not only a position (for example, a coordinate of a center of each of the shots) of each of the shots but also a distortion (expansion and contraction or rotation) of each of the shots may be obtained.
Further, an electron beam drawing apparatus that performs drawing on a substrate based on drawing stripe data that configures drawing data is known (see Proc. of SPIE Vol. 7970 79701A-1 (2011)).
The distortion of the shot may occur during an exposure process to form the shot or other processes including a heating process.
FIG. 10A is a view illustrating nine (3×3) shots on a wafer (substrate) when an expansion and contraction distortion is applied to the shots. A solid line indicates an actual shot and a broken line indicates a design shot (in this case, a center of the “actual” shot matches with a center of the “design” shot).
FIG. 10B illustrates an aspect when the expandable and contractable shot is drawn by a drawing apparatus discussed in Proc. of SPIE Vol. 7970 79701A-1 (2011). FIG. 10B illustrates initial positions B1 to B8 of the electron beam. The wafer moves upwardly while the electron beam scans the wafer left and right to draw a drawing area with a stripe shape (stripe drawing area) on the wafer. Stripe drawing areas S1 to S8 are drawn by electron beams.
Beam blanking is performed on each of the beams by control data according to the drawing data to draw the corresponding stripe drawing area. Control data of each of the beams may be generated by dividing drawing data of the shot in the unit of a stripe (drawing stripe data). Here, if the shot has an expansion and contraction distortion, even though the shot (design shot) represented by the broken line of FIG. 10B is drawn by the control data, an error may occur in the superimposition.
FIG. 10C is a view illustrating nine (3×3) shots on a wafer when the shots have a rotation distortion. In a case where the shot has the rotation distortion, an error occurs in the superimposition, which is illustrated in FIG. 10D. The usage of the solid line and the broken line is the same as in FIGS. 10A and 10B.
In order to reduce such an error, a method that distorts the drawing data based on the distortion of the measured shot and then divides the drawing data in the unit of a stripe to generate control data for every beam is considered. However, this method is inappropriate because this method requires enormous processing time.